Work support with interchangeable closure and sheet removal means

ABSTRACT

AND THE DRIVE MECHANISM IS POSITIONED IN THE APERTURE AFTER THE PRINTING OPERATION IS COMPLETED TO ENGAGE THE UNDERSIDE OF THE PRINTED SHEET AND DRIVE IT LATERALLY ACROSS THE WORK SURFACE IN A REMOVAL OPERATION. A SILK SCREEN PROCESS PRESS HAS AN APERTURE IN ITS WORK SURFACE ON WHICH THE SHEET TO BE PRINTED IS PLACED. A CLOSURE MEMBER IS MOVABLE BETWEEN A POSITION CLOSING THE APERTURE AND A SECOND POSITION REMOTE FROM THE APERTURE. A DRIVE MECHANISM IS MOVABLE BETWEEN A POSITION IN THE APERTURE AND A POSITION REMOTE FROM THE APERTURE

o. M. GILMAN ETAL WORK SUPPORT WITH INTERCHANGEABLE CLOSURE AND Sept. 20, 1971 SHEET REMOVAL MEANS 2 Sheets-Sheet 1.

Filed May 9, 1969 2 Sheets-Sheet 2 D. M. GILMAN ETA!- SI- l EE'1 REMOVAL MEANS WORK SUPPORT WITH INTERCHANGEABLE CLOSURE AND Filed May 9, 1969 FIG United States Patent 3,605,614 WORK SUPPORT WITH INTERCHANGEABLE CLOSURE AND SHEET REMOVAL MEANS David M. Gilman, Brookline, and Louis Gilman, Newtonville, Mass., assignors to Graphic Equipment of Boston,

Inc., Boston, Mass.

Filed May 9, 1969, Ser. No. 823,397 Int. Cl. B41f 15/20 US. Cl. 101-126 12 Claims ABSTRACT OF THE DISCLOSURE A silk screen process press has an aperture in its work surface on which the sheet to be printed is placed. A closure member is movable between a position closing the aperture and a second position remote from the aperture. A drive mechanism is movable between a position in the aperture and a position remote from the aperture and the drive mechanism is positioned in the aperture after the printing operation is completed to engage the underside of the printed sheet and drive it laterally across the work surface in a removal operation.

SUMMARY OF INVENTION This invention relates to material handling apparatus and more particularly to an improved sheet handling apparatus particularly useful in presses designed for silk screen process reproduction.

In printing material with a silk screen process press, sheet material is placed on a flat smooth work surface, and after the screen has been coated evenly with paint, a squeegee is moved across the silk screen to force paint through the screen onto the work sheet. After the print ing stroke has been completed, the silk screen frame is raised and the printed sheet removed. The printed sheets must be carefully handled to avoid damage to either the printing or to the sheet itself. Manual removal of the printed sheets is time consuming. Mechanical arrangements have been proposed for removing sheet material, such as arrangements which grip an unprinted edge of the printed sheet. Such devices have employed complex mechanical linkages which occupy a large amount of space and are frequently awkward to use and to synchronize with the operation of the press.

Accordingly, it is an object of this invention to provide novel and improved sheet handling apparatus particularly adapted for use with a screen process press.

Another object of the invention is to provide a novel and improved sheet handling mechanism arranged for incorporation into a work surface support structure and for automatic operation in sequence with other sheet manipulating operations.

A further object of the invention is to provide novel and improved apparatus for removing sheet material automatically from a printing press of the screen process type.

In accordance with the invention there is provided sheet material handling apparatus that includes a planar work surface for receiving a sheet of material in supporting relation, that surface having an opening therein. A closure member is adapted to be moved between a first position in said opening where it provides a surface continuous with said work surface and a second position remote from the opening and a drive mechanism is adapted to be moved between a first position in the opening and a second position remote from the opening. A positioning mechanism alternatively positions said closure member and said drive mechanism in their respective first positions in the opening. The closure member in its first position supports the sheet material for work thereon and the drive mechanism in its first position engages the lower ice surface of sheet material on the work surface and trans lates the sheet material laterally across the work surface in a sheet removal operation.

In a preferred embodiment the apparatus is employed with a silk screen process press which includes a screen mounted for pivotal movement against the work surface end and squeegee mechanism for applying print material through the screen to a work sheet position on the work surface. A drive unit coordinates the pivotal movement of the screen, the reciprocal movement of the squeegee mechanism and the alternate movement of the closure member and the drive mechanism into the opening in the work surface so that the closure member is disposed in that opening while the squeegee mechanism is being reciprocated and the drive unit is disposed in the open ing to drive the printed sheet laterally across the work surface after the screen has been lifted. In that embodiment the drive mechanism includes an endless belt mounted on a support structure that includes a vacuum chamber. A roller is disposed at either end of the vacuum chamber for supporting the belt and there are a plurality of parallel grooves in the upper surface of the vacuum chamber, together with a centrally located elongated channel that communicates with the chamber. The belt has in its upper surface a series of transversely extending recesses and a perforation is provided in each recess. The perforations are aligned with the elongated channel when the belt is trained over the rollers. When the drive unit is positioned in the opening in the work surface, vacuum applied through the chamber, the elongated chamber and the perforations in the belt provides a force to adhere the sheet to the belt and that belt when driven imparts a lateral translating force to the sheet material.

In the preferred embodiment, two such driving mechanisms are employed and they contact the sheet after it has been printed adjacent the leading lateral edge. These drive mechanisms slide the sheet, after it has been printed,

across the table quickly, efiiciently and without damage to the printed material or to the sheet itself. The arrangement is compact, is housed within the work table support structure and is driven in coordination with the operation of the screen process press from the same power unit as has conventionally been employed for operating the printing mechanism.

Other objects, features and advantages of the invention will be seen as a description of a particular embodiment progresses. It will be understood that the invention is described in connection with this embodiment in an illustrative and not a limiting sense as modifications of this embodiment within the spirit and scope of the invention will be apparent to those skilled in the art. In the drawings:

FIG. 1 is a perspective view of a silk screen process press constructed in accordance with the invention FIG. 2 is a perspective view of the work surface of the press shown in FIG. 1, with portions broken away to show details of the drive mechanism and closure member apparatus;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1 showing the closure member and drive mechanism components in a first position;

FIG. 4 is a sectional view similar to FIG. 3 showing the closure member and drive mechanism components in a second position;

FIG. 5 is a sectional view of one of the drive mechanism components;

FIG. 6 is a sectional view taken along the line 6-6 of FIG. 5;

FIG. 7 is atop view of the drive mechanism structure with the belt removed showing details of the vacuum lock; and

FIG. 8 is a top view of a section of the drive belt component in the drive mechanism shown in FIG. 5.

DESCRIPTION OF PARTICULAR EMBODIMENT The silk screen process press shown in FIG. 1 is of the type shown in Gilman U.S. Pat. 2,975,705 and includes a base 10 on which is positioned supported a planar work surface 12. At the rear edge of surface 12 are two pivot brackets 14, 16 which support a first frame 18 that receives a silk screen and a second frame 20 that supports for reciprocation a filler bar and squeegee mechanism 22. Frames 18 and 20 are pivotally mounted for movement by a drive linkage coupled to power unit 24 housed in base 10 between the position shown in FIG. 1 and a lower position in which the silk screen is in contact with table surface 12. The filler bar-squeegee mechanism is reciprocated while the frame 18 is in lowered position by a second drive linkage also coupled to and driven by power unit 24-.

The support surface 12 has two apertures 26, 28, and plug structures 30, 32 are disposed in those apertures during a printing operation. Each plug structure has a lip 34 (as indicated in FIG. 3) which positions the upper surface 36 of the plug closure in accurate alignment with the work surface 12 so that a continuous and smooth surface work surface is provided when the plugs 30, 32 are in the position shown in FIGS. 1 and 3. Each plug structure is mounted on an arm 38 and coupled to shaft 40 which is supported for rotation by pillow blocks 42 that are secured to the under side of surface 12. One end of lever arm 44 is also connected to shaft 40 and its other end is slidably connected to drive rod 46. That drive rod is normally biased to the right as indicated in FIG. 3 by spring 48 and is moved laterally to the position in FIG. 4 by link 50 operated by drive mechanism 24. In that position the plug structure have been rotated downwardly away from table 12 about the axis of shaft 40 to the position shown in FIG. 4.

Also slidably coupled to drive rod 46 is a second linkage arm 60 which is connected to and rotates drive shaft 62 that is supported by pillow blocks 64. Connected to shaft 62 are lever arms 66, 68, which support drive mechanisms 70, 72. A drive shaft 74 extends between the two drive mechanisms 70, 72 is driven from power unit 24 through belt 76, transition shaft 78 supporting pillow block 80 and drive belt 82.

Movement of drive rod 46 from the position shown in FIG. 3 to the position shown in FIG. 4 rotates the drive units 70, 72 from a retracted position beneath the surface of table 12 to a position in which the top of the drive units protrude through the ports 26, 28, respectively, in surface 12. In the position shown in FIG. 3, drive belt 82 is slack so that shaft 74 is not turning but in the position shown in FIG. 4, belt 82 is under tension and rotates shaft 74 to operate the two drive units 70, 72.

Each drive unit, as illustrated in FIGS. -8 includes two frame members 100 that support two upper rollers 102, 104, the axes of which are spaced two inches apart, and a lower flanged roller 106 about which a one inch wide neoprene belt 108 is trained. Supported on frame members 100 and positioned between rollers 102 and 104 is a vacuum block 110 that has a connection via pipe 112 and tube 113 to a source of low pressure. The vacuum block 110 has, on its upper surface 114 four grooves 115 that extend between rollers 102 and 104 as indicated in FIGS. 6 and 7. In the center of vacuum block and extending parallel to grooves 115 is an elongated tapered vacuum slot 116 that communicates with chamber 118 in the interior of vacuum block 110. Slot 116 at the surface of block 110 has a width of A inch and a length of 1% inch.

The neoprene belt 108, as indicated in FIGS. 5, 6 and 8, includes a series of elongated, generally rectangular recesses 120 each about 'Vsinch long so that they extend across a substantial portion of the width of the belt. In the nt r f ea h ecess 20' is a nch diameter P foration 122 that extends through the belt. Thus when the belt is in position on the drive assembly, each perforation 122 when aligned with vacuum slot 116 is in communication with chamber 118 and the reduced pressure is communicated through slot 116 and the perforations 122 to a sheet of paper on the belt. This reduced pressure is distributed by the elongated recesses 120 across substantially the entire width of the belt. Grooves 115 act to break the vacuum between the belt 108 and vacuum block and thus reduce the resistance to driving movement of the belt.

When a sheet of paper is on surface 12 and the mechanism is in the position shown in FIG. 4, the two belts 108 are driven and suction applied via the vacuum block and the perforations in the belt holds the sheet of paper on surface 12 against the belts 108 so that the sheet is moved laterally by the two drive mechanisms.

In operation, the motion of drive rod 46 is coordinated with the operation of the printing mechanism. Each operational cycle begins with the apparatus shown in the position indicated in FIG. 1, that is, plugs 30 and 32 are in apertures 26, 28 with their upper surfaces flush with the surface of work surface 12 and the screen frame 18 raised above that surface. After a sheet of paper to be printed has been placed on work surface 12 the frame structures 18 and 20 are pivoted downwardly by power unit 24, bringing the screen into contact with the paper to be printed. The squeegee then moves across the screen as driven by power unit 24 from the front edge to the back edge in a printing operation. After the squeegee has passed ports 26 the drive lever 50 is moved by the power unit 24 to the left as indicated in FIGS. 3 and 4, causing both shafts 40 and 62 to rotate in the clockwise direction. This rotation moves plugs 30 and 32 downwardly out of ports 26, 28 and at the same time raises belt conveyer drive units 70 and 72 into those ports so that their upper surface contact the under surface of the printed sheet. This motion is timed so that the drive units 70, 72 do not contact the paper until the printing operation is completed, that is, the frames 18, 20 have been lifted so that the screen does not contact the paper. The drive belts 108 then move the printed sheet laterally off the working surface rapidly, smoothly and without damage to the freshly printed sheet. After sufficient time has elapsed for the sheet of paper to be driven off the sheet onto an appropriate conveyer or to a suitable storage location, the drive mechanism resets by movement of arm 50 to the right as urged by biasing spring 48, removing the drive units 70, 72 from the ports 26, 28 and replacing the closure plugs in those ports. During this operation, another sheet of paper may be placed on work surface and the printing and sheet removal cycle immediately repeated.-

Thus it will be seen that the invention provides a compact and efiicient screen process printing apparatus which includes, housed within the table support structure, a sheet transfer mechanism which operates in coordination with the operation of the printing mechanism and removes sheets after they have been printed quickly, efficiently and without damage to the printed material or the sheet itself. While a particular embodiment of the invention has been shown and described, various modifications thereof will be apparent to those skilled in the art and therefore it is not intended that the invention be limited to the disclosed embodiment or to details thereof and departures may be made therefrom within the spirit and scope of the invention as defined in the claims.

What is claimed is:

1. In a silk screen process press or the like having a planar work surface for receiving a work sheet in supporting relation, and printing mechanism for applying printing material to a work sheet positioned on said work surface, apparatus for removing said work sheet from said work surface after printing comprising a closure member movable between a first position in an opening in said work surface where it provides a surface continuous with said work surface and a second position remote from said opening, a drive mechanism movable between a first position in said opening and a second position remote from said opening, and drive means for disposing said closure member in said opening to provide a continuous planar surface for supporting a work sheet to be printed during operation of said printing mechanism in a printing operation and for removing said closure member from said first position in said opening to said second position after the printing operation has been completed and then moving said drive mechanism from said second position to said first position into said opening to drive the printed sheet laterally across the work surface in a sheet removal operation, said drive mechanism in said first position engaging the lower surface of the work sheet on said work surface and translating said work sheet laterally across said work surface in a sheet removal operation.

2. The apparatus as claimed in claim 1 wherein said closure member is pivotally mounted for movement between its first and second positions, said drive mechanism is pivotally mounted for movement between its first and second positions, and said drive means includes a first link secured to said closure member, a second link secured to said drive mechanism and coupling means connected to said first and second links for providing coordinated movement of said closure member and said drive mechanism between their respective first and second positions.

3. The apparatus as claimed in claim 1 wherein said drive mechanism includes a vacuum connection,

a vacuum block having a chamber communicating with said connection, an upper surface, with a plurality of parallel grooves in said upper surface, and an elongated channel in said upper surface communicating with said chamber,

a pair of rollers, one at each end of said vacuum block, a drive roller, a drive belt coupled in said drive roller, and an endless belt having an upper surface, a series of transversely extending recesses in said upper surface of said belt, a perforation in each said recess, said perforations extending in a line corresponding with said elongated channel when said endless belt is trained around said rollers, said endless belt extending around said rollers and being driven by said drive belt for moving the printed sheet laterally across said work surface when said drive mechanism is in its first position, said drive belt being slack when said drive mechanism is in its second position.

4. The apparatus as claimed in claim 1 wherein said drive mechanism includes an endless belt arranged while being driven in said first position to impart a lateral translating force to sheet material on said work surface.

5. The apparatus as claimed in claim 4 and further including means to apply a pressure dilferential to said sheet material through said belt.

6. The apparatus as claimed in claim 5 wherein said drive mechanism includes structure defining a vacuum chamber, said structure having a port in its upper surface and a roller at either end of said upper surface over which said belt is trained for passage across said upper surface.

7. The apparatus as claimed in claim 6 wherein said belt has a series of transverse recesses in the upper surface of said belt and a perforation in each recess, said perforations travelling along a path aligned with said port when said belt is driven over the upper surface of said vacuum chamber.

8. A silk screen process press having a work surface, a screen mounted for movement against said work surface, squeegee mechanism for applying a printing material through said screen to a work sheet positioned on said work surface, an opening in said work surface, a closure member movable between a first position in said opening where it provides a surface continuous with said work surface and a second position remote from said opening, a drive mechanism movable between a first posi-l tion in said opening and a second position remote from said opening, and drive means for maintaining said closure member disposed in said opening while said screen is against said work surface and said squeegee mechanism is operated and for removing said closure member from said opening and moving said drive mechanism into said opening to drive the printed sheet laterally across the work surface in a removal operation after said screen has been lifted from said work surface.

9. The press as claimed in claim 8 wherein said drive mechanism includes a vacuum connection,

a vacuum block having a chamber communicating with said connection, an upper surface, with a plurality of parallel grooves in said upper surface, and an elongated channel in said upper surface communicating with said chamber,

a pair of rollers, one at each end of said vacuum block, and a drive roller, and an endless belt, having an upper surface, a series of transversely extending recesses in said upper surface of said belt, a perforation in each said recess, said perforations extending in a line corresponding with said elongated channel when said belt is trained around said rollers, said belt extending around said rollers and being driven by said drive roller for moving the printed sheet laterally across said work surface when said drive mechanism is in said first position.

10. The apparatus as claimed in claim 8 wherein said drive mechanism includes an endless belt arranged while being driven in said first position to impart a lateral translating force to sheet material on said work surface.

11. The apparatus as claimed in claim 9 and further including means to apply a pressure differential to said sheet material through said belt.

12. The apparatus as claimed in claim 11 wherein said drive mechanism includes structure defining a vacuum chamber, said structure having a port in its upper surface and a roller at either end of said upper surface over which said belt is trained for passage across said upper surface.

References Cited UNITED STATES PATENTS 2,963,964 12./1960 Klump 101-126UX 3,081,996 3/1963 Hajos 271-74 3,190,644 6/1965 Schwebel 27l--74X 3,293,998 12/ 1966 Farnow -n 27l-74X 3,359,150 12/1967 Stoothoff et al. 271-74X 3,425,610 2/1969 Stewart 271--74X 3,505,951 4/1970 Gartrell 10l-126X ROBERT E. PULFREY, Primary Examiner R. E. SUTER, Assistant Examiner US. Cl. X.R. 271-74 

